Precision navigation systems can be used for aircraft landing systems, such as landing aircraft on a moving platform, Local Area Augmentation System (LAAS) or Ground Based Augmentation System (GBAS). A precision aircraft landing system is a navigation aid that can assist aircraft in landing in a wide range of environments. For example, the aircraft landing system can guide the aircraft to a landing platform onboard a ship or to a makeshift airfield. The aircraft landing system can provide real-time differential correction of GPS signals to aid the aircraft in landing on the landing platform. Differential GPS can provide improved location accuracy, such as from the 15-meter nominal GPS accuracy to approximately 10 centimeters (cm). Local reference receivers, such as global positioning system (GPS) sensors can be installed on the landing platform. The landing platform can be at an airport or onboard an aircraft carrier. The local reference receivers can be located around the landing platform at precisely surveyed locations.
In one example, the aircraft landing system can include at least three local reference receivers (e.g., GPS sensors or GPS receivers), a central processing system, and a transmitter, such as a very high frequency (VHF) data broadcast (VDB) transmitter. The local reference receivers can receive GPS signals from a plurality of GPS satellites. Each local reference receiver can measure a time of transmission between a GPS satellite and the local reference receiver and a travel distance of the GPS signal. The aircraft landing system can compare the measured distance with an actual distance based on a broadcast satellite position and a true local reference receiver position. A correction value can be determined based on a difference between the measured distance and the actual distance. The correction value can be used to formulate a correction message, which can be transmitted to a receiver onboard the aircraft via the VDB transmitter. The receiver onboard the aircraft can use the correction message to more accurate compute the aircraft's GPS position, velocity and time to guide the aircraft safety to the landing platform.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.